Sea levels could rise by 'metres' because Antarctic ice is melting six times as quickly as before, scientists have warned.

Millions of people living in coastal cities around the world could be threatened with flooding as the pace of melting is expected to lead to disastrous sea level rise in the years to come, a study has claimed.

"As the Antarctic ice sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries," study lead Eric Rignot, chair of Earth system science at the University of California, said.

"The Wilkes Land sector of East Antarctica has, overall, always been an important participant in the mass loss, even as far back as the 1980s, as our research has shown," Mr Rignot said.

"This region is probably more sensitive to climate than has traditionally been assumed, and that's important to know, because it holds even more ice than West Antarctica and the Antarctic Peninsula together," he added.

Warming ocean water will only speed up ice loss in the future, Mr Rignot said.

The report, following the longest-ever assessment of ice mass in the Antarctic, was published in the Proceedings of the National Academy of Sciences (PNAS).